aws-mock doesn't seem to be compatible with the latest version of awscli.
aws --endpoint-url http://localhost:8000/aws-mock ec2 describe-instances --region us-east-1
Unable to parse response (not well-formed (invalid token): line 3, column 14), invalid XML received:
b'<HTML><HEAD><TITLE>Directory: /aws-mock/</TITLE></HEAD><BODY>\n<H1>Directory: /aws-mock/</H1>\n<TABLE BORDER=0>\n\n<TR><TD><A HREF="/aws-mock/META-INF/">META-INF/ </TD><TD ALIGN=right>4096 bytes </TD><TD>Sep 12, 2017 8:59:01 PM</TD></TR>\n<TR><TD><A HREF="/aws-mock/WEB-INF/">WEB-INF/ </TD><TD ALIGN=right>4096 bytes </TD><TD>Sep 12, 2017 8:59:01 PM</TD></TR></TABLE>\n</BODY></HTML>\n'